Excited States of Bound Excitons and Neutral Donors in CdS

1971 ◽  
Vol 49 (19) ◽  
pp. 2432-2439 ◽  
Author(s):  
H. Malm ◽  
R. R. Haering
Keyword(s):  
Binding Energy ◽  
Excited States ◽  
Complex I ◽  
Radiative Decay ◽  
Energy Levels ◽  
Auger Process ◽  
Neutral Donor ◽  
New Information ◽  
Donor Binding Energy ◽  
Low Temperature Photoluminescence

A technique employing a monochromator to select the incident photon energy and a spectrometer to analyze the low temperature photoluminescence of CdS crystals has proven to be valuable, both in analyzing the usual photoluminescent spectra and in obtaining new information on excited states of bound excitons and excited states of neutral donors in the crystal. An accurate measurement of the donor energy levels and the donor binding energy gave a binding energy for the Cl donor in CdS of 33.0 ± 0.2 meV. Energies of excited states of the bound exciton complexes were also measured and for the bound exciton – neutral donor complex (I2 complex) some seven excited state levels were found. One type of radiative decay observed for this I2 complex is a radiative Auger process. This has important consequences in interpreting photoconductivity spectra.

EFFECT OF Γ-X CROSSOVER ON THE DONOR BINDING ENERGY IN A QUANTUM WELL

2005 ◽  
Vol 19 (25) ◽  
pp. 3861-3868 ◽  
Author(s):  
P. NITHIANANTHI ◽  
K. JAYAKUMAR
Keyword(s):  
Hydrostatic Pressure ◽  
Binding Energy ◽  
Quantum Well ◽  
Excited States ◽  
Conduction Band ◽  
Ground State ◽  
External Hydrostatic Pressure ◽  
Donor Binding Energy ◽  
Dielectric Screening

The effect of Γ-X crossover due to the external hydrostatic pressure on the ground state donor binding energy as well as for some low lying excited states for a Quantum well has been investigated by considering the non-parabolicity of the conduction band and pressure dependent spatial dielectric screening. It is observed that the effect of Γ-X crossover is predominant for ground state than for low lying excited states.

Low temperature photoluminescence and deformation luminescence of microparticles SrAl2O4:(Eu2+, Dy3+) in a matrix of photopolymer

2014 ◽  
Vol 28 (23) ◽  
pp. 1450154 ◽  
Author(s):  
A. A. Banishev ◽  
A. A. Lotin ◽  
A. F. Banishev
Keyword(s):  
Low Temperature ◽  
Energy Levels ◽  
Visible Region ◽  
Short Wave ◽  
Disperse Powder ◽  
Wave Band ◽  
New Information ◽  
Fine Disperse ◽  
Low Temperature Photoluminescence ◽  
Impurities And Defects

The paper deals with low-temperature photoluminescence and deformation luminescence (mechanoluminescence) of a composite material based on fine disperse powder of phosphor SrAl 2 O 4:( Eu 2+, Dy 3+) and photopolymerizing resin that is transparent in the visible region. New information about the energy levels of impurities and defects was obtained. It has been found that at low temperatures (T = 15 ÷ 200 K) the photoluminescence spectrum of SrAl 2 O 4:( Eu 2+, Dy 3+) presents two partially overlapping wide bands with the maxima at λ1 max = 446 nm and λ2 max = 517 nm. The strong interaction of energy states of the bands results in temperature quenching of the short-wave band of luminescence (λ1 max = 446 nm) and its complete attenuation at T ≥ 200 K. The results were used to describe the mechanism of persistent luminescence and mechanoluminescence of SrAl 2 O 4:( Eu 2+, Dy 3+).

Optical Properties for ZnSe Epilayer Obtained From Photoluminescience Measurement

2006 ◽  
Vol 321-323 ◽  
pp. 1306-1308
Author(s):  
Sang Youl Lee ◽  
Kwang Joon Hong
Keyword(s):  
Optical Properties ◽  
Binding Energy ◽  
Low Temperature ◽  
Gaas Substrate ◽  
Exciton Peak ◽  
Neutral Donor ◽  
Hot Wall Epitaxy ◽  
Neutral Acceptor ◽  
Low Temperature Photoluminescence ◽  
Zn Vacancy

The ZnSe epilayers were grown on the GaAs substrate by hot wall epitaxy. After the ZnSe epilayers treated in the vacuum-, Zn-, and Se-atmosphere, respectively. The defects of the epilayer were investigated by means of the low-temperature photoluminescence measurement. The dominant peaks at 2.7988 eV and 2.7937 eV obtained from the PL spectrum of the as-grown ZnSe epilayer were found to be consistent with the upper and the lower polariton peak of the exciton, I2 (Do, X), bounded to the neutral donor associated with the Se-vacancy. This donorimpurity binding energy was calculated to be 25.3 meV. The exciton peak, I1 d, at 2.7812 eV was confirmed to be bound to the neutral acceptor corresponded with the Zn-vacancy.

Photoluminescence, Reflectance, and Magnetospectroscopy of Shallow Excitons in GaN

1996 ◽  
Vol 449 ◽  
Author(s):  
B. J. Skromme ◽  
H. Zhao ◽  
B. Goldenberg ◽  
H. S. Kong ◽  
M. T. Leonard ◽  
...  
Keyword(s):  
Binding Energy ◽  
Molecular Beam ◽  
Free Exciton ◽  
Chemical Vapor ◽  
Exciton Binding Energy ◽  
Exciton Peak ◽  
Neutral Donor ◽  
Gas Source ◽  
Donor Binding Energy ◽  
First Time

ABSTRACTWe report several new aspects of the excitonic properties of heteroepitaxial GaN grown on sapphire or 6H-SiC. In particular, we observed the n = 2 free exciton associated with both A and B excitons (which are distinct from the n = 1 C exciton) using reflectance and 1.7 K photoluminescence. We also studied the behavior of the n = 2 A-exciton using magnetoluminescence in fields up to 12 T. The large diamagnetic shift and splitting positively confirm the identification, yielding an exciton binding energy of about 26.4 meV. Several previous identifications of the n = 2 free exciton yielding a smaller exciton binding energy are probably in error, based on our results. We have also detected the two-electron replica of the neutral donor-bound exciton for the first time in GaN and observed its splitting pattern in magnetic fields up to 12 T. This feature is 22 meV below the principal neutral donor-bound exciton peak, independently of strain shifts in the overall spectrum. It yields a precise donor binding energy of 29 meV for the shallow residual donor in material grown by metalorganic chemical vapor deposition and gas-source molecular beam epitaxy, considerably smaller than that of the residual donor reported earlier in hydride vapor phase epitaxial material (about 35.5 meV).

Restriction of Access to Dark State: A New Mechanistic Model for Heteroatom-Containing AIE Systems

2019 ◽  
Author(s):  
Yujie Tu ◽  
Junkai Liu ◽  
Haoke Zhang ◽  
Qian Peng ◽  
Jacky W. Y. Lam ◽  
...  
Keyword(s):  
Excited States ◽  
Radiative Decay ◽  
Molecular Design ◽  
Mechanistic Model ◽  
Zinc Ion ◽  
Easy Access ◽  
Triplet States ◽  
Dark State ◽  
Ion Probe ◽  
Π State

Aggregation-induced emission (AIE) is an unusual photophysical phenomenon and provides an effective and advantageous strategy for the design of highly emissive materials in versatile applications such as sensing, imaging, and theragnosis. "Restriction of intramolecular motion" is the well-recognized working mechanism of AIE and have guided the molecular design of most AIE materials. However, it sometimes fails to be workable to some heteroatom-containing systems. Herein, in this work, we take more than one excited state into account and specify a mechanism –"restriction of access to dark state (RADS)" – to explain the AIE effect of heteroatom-containing molecules. An anthracene-based zinc ion probe named APA is chosen as the model compound, whose weak fluorescence in solution is ascribed to the easy access from the bright (π,π*) state to the closelying dark (n,π*) state caused by the strong vibronic coupling of the two excited states. By either metal complexation or aggregation, the dark state is less accessible due to the restriction of the molecular motion leading to the dark state and elevation of the dark state energy, thus the emission of the bright state is restored. RADS is found to be powerful in elucidating the photophysics of AIE materials with excited states which favor non-radiative decay, including overlap-forbidden states such as (n,π*) and CT states, spin-forbidden triplet states, which commonly exist in heteroatom-containing molecules.

Energy levels of ground and singly excited states of two-electron atoms in dense quantum plasmas

2021 ◽  
pp. 101420
Author(s):  
Yong Zhi Zhang ◽  
Li Guang Jiao ◽  
Fang Liu ◽  
Ai Hua Liu ◽  
Yew Kam Ho
Keyword(s):  
Excited States ◽  
Energy Levels ◽  
Quantum Plasmas

Energy Levels of Core-Excited States and Atomic Oscillator Strengths for Boron and Boron-like Ions (abstract)

2009 ◽  
Author(s):  
Magda A. Rahim ◽  
Beverly Karplus Hartline ◽  
Renee K. Horton ◽  
Catherine M. Kaicher
Keyword(s):  
Excited States ◽  
Energy Levels ◽  
Oscillator Strengths

scholarly journals X-ray laser lines in nickel-like erbium

2016 ◽  
Vol 94 (8) ◽  
pp. 705-711
Author(s):  
Wessameldin S. Abdelaziz
Keyword(s):  
Ionization Potential ◽  
Excited States ◽  
Ground State ◽  
Energy Levels ◽  
Single Electron ◽  
Electron Densities ◽  
X Ray ◽  
Electron Excited States

Energy levels of 249 excited levels in nickel-like erbium are calculated using the 3s23p63d10 as a ground state and the single electron excited states from n = 3 to n = 4, 5 orbitals, calculations have been performed using FAC code (Gu. Astrophys. J. 582, 1241 (2003). doi:10.1086/344745 ). The populations are calculated over electron densities from 1020 to 1023 cm−3 and electron temperatures 1/2, 3/4 of the ionization potential of Ni-like Er. The gain coefficients of the transitions are calculated.

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